Electrical connectors are used in many electronic systems. It is generally easier and more cost effective to manufacture a system on several printed circuit boards that are then joined together with electrical connectors. A traditional arrangement for joining several printed circuit boards is to have one printed circuit board serve as a backplane. Other printed circuit boards, called daughter boards, are connected through the backplane.
A traditional backplane is a printed circuit board with many connectors. Conducting traces in the printed circuit board connect to signal pins in the connectors so signals may be routed between the connectors. Daughter boards also contain connectors that are plugged into the connectors on the backplane. In this way, signals are routed among the daughter boards through the backplane. The daughter cards often plug into the backplane at a right angle. The connectors used for these applications contain a right angle bend and are often called xe2x80x9cright angle connectors.xe2x80x9d
Connectors are also used in other configurations for interconnecting printed circuit boards, and even for connecting cables to printed circuit boards. Sometimes, one or more small printed circuit boards are connected to another larger printed circuit board. The larger printed circuit board is called a xe2x80x9cmother boardxe2x80x9d and the printed circuit boards plugged into it are called daughter boards. Also, boards of the same size are sometimes aligned in parallel. Connectors used in these applications are sometimes called xe2x80x9cstacking connectorsxe2x80x9d or xe2x80x9cmezzanine connectors.xe2x80x9d
Regardless of the exact application, electrical connector designs have generally needed to mirror trends in the electronics industry. Electronic systems generally have gotten smaller and faster. They also handle much more data than systems built just a few years ago. These trends mean that electrical connectors must carry more and faster data signals in a smaller space without degrading the signal. Constraints imposed by the geometries of backplanes designed for certain applications however, reduce the options available for possible connector solutions.
For example, thick, large backplanes make some surface mount connectors impractical as the number of layers in the board hinders raising the board to a temperature necessary to solder the leads to the board. Press fit connectors require larger vias. As via diameters increase, the capacitance of the via also increases thus making an impedance match between the connector and the characteristic impedance of a transmission line on the backplane more difficult.
Connectors which make contact through pressure are sometimes referred to as xe2x80x9cpressure mountedxe2x80x9d or z-axis pressure mount connectors as the pressure applied to the connector to provide the desired contact is typically exerted in the z-axis direction. These pressure mount connectors provide the low electrical parasitics desired by current industry trends.
Connectors that join optical fibers to create a low loss, separable optical interface have been available and in use for a number of years.
These connectors use a variety of ferrule types, alignment schemes and latching mechanisms for joining solitary strands of single-mode and multi-mode optical fiber as well as a multiplicity of fibers in a ribbon form. An example of the second is typified by the xe2x80x9cMTxe2x80x9d style array ferrules. Each of these connectors join the fibers end to end using a variety of alignment techniques. For single fiber joints, an alignment ferrule generally surrounds and guides the fiber-ends together.
One application of optical connector technology is to provide an optical path for signals from board to board, or shelf to shelf within equipment chassis. This optical path is provided by passing optical fibers perpendicularly through a backplane, using so-called xe2x80x9cpass throughxe2x80x9d optical connectors. A right angle mounting of connectors join the optical fibers from an optical module on the daughtercard to optical fibers in cables running out of a card rack. This right angle mounting relies upon a blind mating of the fibers and must conform to standard cable management conventions such as minimum bend radius that contribute to box volume requirements behind the backplane.
As the need for bandwidth capacity increases, xe2x80x9cOptical Backplanesxe2x80x9d usually in the form of laminated fiber matrices that overlay the backplane or that supplement the backplane are also being used. These optical backplanes, likewise have their fibers terminated to standard xe2x80x9cpass throughxe2x80x9d optical connectors as previously described.
Current means for actuating z-axis pressure mount connectors typically involved bolting the circuit board, connector, and second circuit board together with screws and a form of reinforcing plate. Due to the nature of the fixturing used, these types of interfaces do not typically lend themselves to traditional, right angle daughtercard/backplane interfaces.
The current implementations of xe2x80x9coptical backplanexe2x80x9d or intra-box optical connections suffer as a result of the nature of the xe2x80x9cpass throughxe2x80x9d optical interface onto the equipment backplane. A 90 degree turn by the optical fiber on the backplane is required. Current optical fiber technology requires the design to maintain a bend radius of greater than one inch to avoid optical loss and mechanical fatigue that can cause breakage. Fixtures that control the fiber bend radius are typically used. These fixtures gradually turn the fiber parallel to the backplane in order to plug to an overlay. Alternatively, fibers may be looped from one perpendicular xe2x80x9cpass throughxe2x80x9d to another to effect slot to slot connectivity. Both of these options, however, consume considerable space behind the traditional electrical backplane while radius fixtures add additional cost to the system.
One solution described in the following disclosure provides a connector fixture for enabling a z-axis, pressure mount connection. The connector fixture includes a slot, an actuator, responsive to engagement by a circuit board inserted into the slot and a loading spring, responsive to rotation of the actuator, for compressing against a surface of a z-axis, pressure mount connector. With such an arrangement, a pressure mount connector can be used in a right angle mounting configuration.
Another solution described in the following disclosure provides a connector fixture for enabling an electro-optical connection. The connector fixture includes a slot, an actuator, responsive to engagement by a circuit board inserted into the slot, a channel for accepting an optical fiber and a loading spring, responsive to rotation of said actuator, for compressing against a surface of the electro-optical connector. With such an arrangement, a means for launching into an optical fiber positioned perpendicular to the circuit board is facilitated.